Aztec
From Memory Alpha, the free Star Trek reference.
The Aztec Native American Human civilization existed in the southern regions of North America (an area that would later include the nation-state of Mexico) on Earth in the 14th, 15th and 16th centuries.
Kukulkan, a benevolent alien being, periodically visited ancient Earth civilizations and influenced their architecture and agricultural development, and was worshiped as a god. Prior to visiting the predecessors of the Aztecs in the 12th century, Kulkulkan had influenced the Egyptian and Mayan cultures. Kulkulkan was discovered by the crew of the USS Enterprise in 2270. (TAS: "How Sharper Than a Serpent's Tooth")
